CODEWITHSUNDEEP
cstaticinitialization
NotDuplicateSL
NotDuplicateSL

Reputation: 129

C Static variables on function inputs

I'd like to save an input to a function and manipulate it across multiple calls. However, if I do the following...

int testFunc(char *toString) {
        static char *toChange = toString;
        static int counter = 0;

        toChange[counter] = 'A';
        printf("String is being corrupted... %s\n", toChange);
        counter++;

        return 0;
}

I get an error saying that the input toChange cannot be set to a non-static variable. I have been trying to figure out how to get around this but I cannot find any answers.

Upvotes: 1

Views: 136

Answers (2)

Vlad from Moscow
Vlad from Moscow

Reputation: 310920

Static variables shall be initialized by constant expressions.

Write instead something like

 int testFunc(char *toString) {
    static char *toChange;
    static int counter;

    if ( toChange == NULL || toString == NULL ) 
    {
        toChange = toString;
        counter = 0;
    } 

    toChange[counter] = 'A';
    printf("String is being corrupted... %s\n", toChange);
    counter++;

    return 0;

}

Upvotes: 2

Eduardo Fernandes
Eduardo Fernandes

Reputation: 403

Do this:

int testFunc(char *toString) {
    static char *toChange = NULL;
    static int counter = 0;
    if (toChange == NULL) {
        toChange = (char*)malloc(strlen(toString) + 1);
        memset(toChange, 0, strlen(toString) + 1);
        strcpy(toChange, toString);
    }
    toChange[counter] = 'A';
    printf("String is being corrupted... %s\n", toChange);
    counter++;
    return 0;
}

Upvotes: 0

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